Re: [volt-nuts] Voltage Reference.
Hello Dan, yes the thermal shield is standard on all LM399. But additional thermal shielding of the pins/housing on both sides of the PCB will improve stability (noise + tilting effects). Since National Semiconductors (TI) has discontinued the LM399, Linear Technology is now the only manufacturer. DigiKey has the LM399 on stock. With best regards Andreas Am 05.11.2014 um 20:02 schrieb Dan Kemppainen: Andreas, If I proceed down this path, it will be a learning experience. As with most learning projects, a bit of 'overkill' is usually present. It's just plain old fun to over engineer something! :) The LM399 does look like a nice package. Do they all come with the thermal shield, or is that an option that needs to be purchased separately? Dan On 11/5/2014 12:00 PM, volt-nuts-requ...@febo.com wrote: Message: 1 Date: Tue, 04 Nov 2014 19:20:09 +0100 From: Andreas Jahn To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] Voltage Reference. Message-ID: <545918d9.2020...@t-online.de> Content-Type: text/plain; charset=utf-8; format=flowed Hello Dan, If you dont need the low noise and long term stability of the LTZ1000 then the LM399 will do the job without special resistors (like T.C. less than 5ppm/K). The only thing that I recommend is to do a good thermal isolation for the references. With best regards Andreas ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Voltage Reference.
Andreas, If I proceed down this path, it will be a learning experience. As with most learning projects, a bit of 'overkill' is usually present. It's just plain old fun to over engineer something! :) The LM399 does look like a nice package. Do they all come with the thermal shield, or is that an option that needs to be purchased separately? Dan On 11/5/2014 12:00 PM, volt-nuts-requ...@febo.com wrote: > Message: 1 > Date: Tue, 04 Nov 2014 19:20:09 +0100 > From: Andreas Jahn > To: Discussion of precise voltage measurement > Subject: Re: [volt-nuts] Voltage Reference. > Message-ID: <545918d9.2020...@t-online.de> > Content-Type: text/plain; charset=utf-8; format=flowed > > Hello Dan, > > If you dont need the low noise and long term stability of the LTZ1000 then > the LM399 will do the job without special resistors (like T.C. less than > 5ppm/K). > > The only thing that I recommend is to do a good thermal isolation for > the references. > > With best regards > > Andreas ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Voltage Reference.
Hello Dan, If you dont need the low noise and long term stability of the LTZ1000 then the LM399 will do the job without special resistors (like T.C. less than 5ppm/K). The only thing that I recommend is to do a good thermal isolation for the references. With best regards Andreas Am 04.11.2014 um 15:10 schrieb Dan Kemppainen: Rob and Andreas, Thanks for the feedback. You both brought up plastic housings as a concern. It was an issue in the back of my mind also. Rob, I did get your email directly, but not the one on the list. Weird. Andreas, I always see references to the LM399 and LTZ1000. I was just going through the mental exercise of 'what if'. Of course, it appears you have gone through the real exercise of 'what if'! So, it appears that the LTZ1000 is still the best there is. I see they are available the linear web site, so may pick one up to play with this winter. Thanks for the input! Dan Hello Dan, If you look for sub-ppm then also noise or hysteresis might be a issue. Nearly all good references have around 0.6ppm low frequency noise with respect to output voltage. (giving 3uVpp for 5V). I have tested 2 VRE3050A for noise and one for TC. In the range of 16-40 deg C average tempco was low (about 8 ppm over 16-40 deg) (nearly zero around 28 deg C) but hysteresis at 25 deg was 4 ppm and 0.1-10 Hz noise around 9uVpp. The second VRE I have only tested for noise which gave also around 9 uVpp. I do not know if both devices are "mondays" devices since I bought them at a time shortly after Thaler was sold to APEX. And current consumption was far below the value of the datasheet. But for me I decided that they are no good value for money for my needs. For the same money you get 5 AD586LQ with <3uVpp noise and nearly no hysteresis in the above temperature range. Ok perhaps you have to select them for tempco. In my case tempco is compensated by a microcontroller with a (NTC) temperature sensor. The ADR4550 suffers like nearly all plastic housings from large hysteresis and perhaps from humidity sensitivity. I measured a nearly linear average tempco of -2ppm/K on one sample. Hysteresis around 16ppm at 25 deg C. Noise was around 3uVpp like good buried zener devices. The LM399 that I have tested are far better in T.C. than the 1ppm/K that are stated in the datasheet. At least this is true around room temperature (10-40 deg C). Only noise is rather different from device to device. Some around the 0.6 ppm others are a factor of 2 or so larger in noise. So perhaps you will have to select for noise. Some Info of other features of LM399 (tilting drift, termal isolation) can be found here: http://www.eevblog.com/forum/projects/lm399-based-10-v-reference/ If you need low T.C. and low noise there is nearly no way not to use the LTZ1000 http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/ With best regards Andreas ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Voltage Reference.
Rob and Andreas, Thanks for the feedback. You both brought up plastic housings as a concern. It was an issue in the back of my mind also. Rob, I did get your email directly, but not the one on the list. Weird. Andreas, I always see references to the LM399 and LTZ1000. I was just going through the mental exercise of 'what if'. Of course, it appears you have gone through the real exercise of 'what if'! So, it appears that the LTZ1000 is still the best there is. I see they are available the linear web site, so may pick one up to play with this winter. Thanks for the input! Dan > > Hello Dan, > > If you look for sub-ppm then also noise or hysteresis might be a issue. > Nearly all good references have around 0.6ppm low frequency noise with > respect to output voltage. > (giving 3uVpp for 5V). > > I have tested 2 VRE3050A for noise and one for TC. > In the range of 16-40 deg C average tempco was low (about 8 ppm over > 16-40 deg) > (nearly zero around 28 deg C) > but hysteresis at 25 deg was 4 ppm and 0.1-10 Hz noise around 9uVpp. > The second VRE I have only tested for noise which gave also around 9 uVpp. > I do not know if both devices are "mondays" devices since I bought them > at a time shortly after Thaler was sold to APEX. > And current consumption was far below the value of the datasheet. > But for me I decided that they are no good value for money for my needs. > > For the same money you get 5 AD586LQ with <3uVpp noise and nearly no > hysteresis in the above temperature range. > Ok perhaps you have to select them for tempco. In my case tempco is > compensated by a microcontroller with a (NTC) temperature sensor. > > The ADR4550 suffers like nearly all plastic housings from large > hysteresis and perhaps from humidity sensitivity. > I measured a nearly linear average tempco of -2ppm/K on one sample. > Hysteresis around 16ppm at 25 deg C. > Noise was around 3uVpp like good buried zener devices. > > The LM399 that I have tested are far better in T.C. than the 1ppm/K that > are stated in the datasheet. > At least this is true around room temperature (10-40 deg C). > Only noise is rather different from device to device. > Some around the 0.6 ppm others are a factor of 2 or so larger in noise. > So perhaps you will have to select for noise. > > Some Info of other features of LM399 (tilting drift, termal isolation) > can be found here: > http://www.eevblog.com/forum/projects/lm399-based-10-v-reference/ > > If you need low T.C. and low noise there is nearly no way not to use the > LTZ1000 > http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/ > > With best regards > > Andreas > ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Voltage Reference.
In message <5454c970.40...@t-online.de>, Andreas Jahn writes: >Further Peltiers have one disadvantage that I do not want to have in >precision cirquits: >The cold side is always collecting humidity. Only if you cool below the dewpoint. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Voltage Reference.
Hello Poul, You are right: Since I use usually battery supply I do not want any heating/cooling. And since the references that I use are only for measuring voltages in a kind of "voltmeter" I can easily compensate the effect of temperature by calculation. On the other side also a reference can be stabilized by a NTC in a small temperature range. See Geller Labs SVR-T. http://www.gellerlabs.com/svr%20series.htm Further Peltiers have one disadvantage that I do not want to have in precision cirquits: The cold side is always collecting humidity. with best regards Andreas Am 01.11.2014 um 12:13 schrieb Poul-Henning Kamp: In message <54549b2c.9070...@t-online.de>, Andreas Jahn writes: Ok perhaps you have to select them for tempco. In my case tempco is compensated by a microcontroller with a (NTC) temperature sensor. Don't underestimate how easy it is to make a oven with a peltier. If you just want to stabilize the temperature around ambient, you need very little power to a peltier to do that, and it can move heat both ways. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Voltage Reference.
In message <54549b2c.9070...@t-online.de>, Andreas Jahn writes: >Ok perhaps you have to select them for tempco. In my case tempco is >compensated by a microcontroller with a (NTC) temperature sensor. Don't underestimate how easy it is to make a oven with a peltier. If you just want to stabilize the temperature around ambient, you need very little power to a peltier to do that, and it can move heat both ways. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Voltage Reference.
Hello Dan, If you look for sub-ppm then also noise or hysteresis might be a issue. Nearly all good references have around 0.6ppm low frequency noise with respect to output voltage. (giving 3uVpp for 5V). I have tested 2 VRE3050A for noise and one for TC. In the range of 16-40 deg C average tempco was low (about 8 ppm over 16-40 deg) (nearly zero around 28 deg C) but hysteresis at 25 deg was 4 ppm and 0.1-10 Hz noise around 9uVpp. The second VRE I have only tested for noise which gave also around 9 uVpp. I do not know if both devices are "mondays" devices since I bought them at a time shortly after Thaler was sold to APEX. And current consumption was far below the value of the datasheet. But for me I decided that they are no good value for money for my needs. For the same money you get 5 AD586LQ with <3uVpp noise and nearly no hysteresis in the above temperature range. Ok perhaps you have to select them for tempco. In my case tempco is compensated by a microcontroller with a (NTC) temperature sensor. The ADR4550 suffers like nearly all plastic housings from large hysteresis and perhaps from humidity sensitivity. I measured a nearly linear average tempco of -2ppm/K on one sample. Hysteresis around 16ppm at 25 deg C. Noise was around 3uVpp like good buried zener devices. The LM399 that I have tested are far better in T.C. than the 1ppm/K that are stated in the datasheet. At least this is true around room temperature (10-40 deg C). Only noise is rather different from device to device. Some around the 0.6 ppm others are a factor of 2 or so larger in noise. So perhaps you will have to select for noise. Some Info of other features of LM399 (tilting drift, termal isolation) can be found here: http://www.eevblog.com/forum/projects/lm399-based-10-v-reference/ If you need low T.C. and low noise there is nearly no way not to use the LTZ1000 http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/ With best regards Andreas Am 31.10.2014 um 20:09 schrieb Dan Kemppainen: Hi All, I'm working on something that requires a stable voltage reference. Long term stability isn't needed, but good thermal stability is. In other words it would be nice to have sub ppm/C temperature, but a few ppm/month or even per day isn't an issue. Anyway, it got me thinking about building a reference for fun, with some of the newer IC's available, but doing so in an ovenized housing. I know the LM399's and LTZ1000's are out there, but has anyone looked at any of the newer IC's out there? For example this one seems to have pretty good ppm/C drift: http://www.digikey.com/product-detail/en/VRE3025JS/598-1916-ND/2036526 However it's not cheap. And this one looks pretty good for the sub $10 price. http://www.digikey.com/product-detail/en/ADR4550BRZ/ADR4550BRZ-ND/3196874 This is the one I was thinking about parking in an oven. It has a turnover around 70C. Has anyone played with inexpensive reference chips, and tried to make a good reference out of them? Any thoughts or comments welcome! Dan ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Voltage Reference.
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Re: [volt-nuts] Voltage Reference.
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Re: [volt-nuts] Voltage Reference.
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[volt-nuts] Voltage Reference.
Hi All, I'm working on something that requires a stable voltage reference. Long term stability isn't needed, but good thermal stability is. In other words it would be nice to have sub ppm/C temperature, but a few ppm/month or even per day isn't an issue. Anyway, it got me thinking about building a reference for fun, with some of the newer IC's available, but doing so in an ovenized housing. I know the LM399's and LTZ1000's are out there, but has anyone looked at any of the newer IC's out there? For example this one seems to have pretty good ppm/C drift: http://www.digikey.com/product-detail/en/VRE3025JS/598-1916-ND/2036526 However it's not cheap. And this one looks pretty good for the sub $10 price. http://www.digikey.com/product-detail/en/ADR4550BRZ/ADR4550BRZ-ND/3196874 This is the one I was thinking about parking in an oven. It has a turnover around 70C. Has anyone played with inexpensive reference chips, and tried to make a good reference out of them? Any thoughts or comments welcome! Dan ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
